1. Field of the Invention
The field of the invention relates to assemblies for collecting blood or other body fluids, the assemblies being of the type including a container having a closure assembly pierceable by a needle or cannula.
2. Description of the Related Art
Blood collection tubes are commonly used by doctors, nurses and other persons to draw a sample of a body fluid from a patient or to receive a fluid sample from another vessel. Such tubes are ordinarily evacuated, and include a pierceable closure. During one typical use of a blood collection tube, one end of a double-ended needle assembly is used to pierce a vein. The evacuated blood collection tube is then urged towards the second end of the double-ended needle assembly until its closure is pierced. Blood is thereby drawn into the tube.
The double-ended needle assembly is ordinarily mounted to a holder having a tubular body. The blood collection tube is inserted within the tubular body in order to engage the second end of the double-ended needle assembly.
The maintenance of a vacuum within the blood collection tube is important. Blood collection tubes may be stored for considerable lengths of time before they are used. Loss of vacuum during storage or at any time can render the collection tube less effective or useless.
A number of designs of blood collection tubes and their closures have been the subjects of patents and other disclosures. British Patent Specification 1 388 494 and U.S. Pat. No. 4,327,746 both disclose closures for such tubes having sealing membranes positioned between a cap and the open end of the collection tube. U.S. Pat. No. 5,061,263 discloses several closure designs, each including a cap, a gas barrier member and a re-sealable member.
U.S. Pat. Nos. 4,150,666, 4,967,919, 4,991,601, 5,326,534, 5,494,170 and International Publication No. WO 81/01238 disclose various blood collection tubes and/or holders for such tubes. The '170 patent discloses a cap having flexible tabs which engage the wall of the holder, thereby maintaining the blood collection tube within the holder.